In some image forming apparatuses such as printers, facsimile machines, copiers, and multifunction peripherals, image formation (involving recording, printing, transfer, etc., of an image) is carried out using a liquid discharge device. Such a liquid discharge device typically includes a write head configured to discharge a liquid droplet onto a medium (such as a recorded/recording medium, a transfer material, and a recording paper; the material of the medium is not particularly limited) as the medium is transported.
The term “image forming apparatus” herein refers to a device for forming an image on a medium of various materials, such as paper, thread, fiber, fabrics, leather, metals, plastics, glass, wood, and ceramics, by discharging a liquid onto such a medium. The term “image formation” herein refers to the formation of not just some image with an intended meaning, such as a character or a diagram, but it also refers to the process of providing a medium with some image without any intended meaning, such as a random pattern. The term “ink” herein does not refer to any specific ink in a narrow sense but it generally refers to liquids that can be used for image formation. The term “liquid discharge device” herein refers to a device for discharging a liquid out of a liquid discharge head.
In an image forming apparatus fitted with such a liquid discharge device, an ink cartridge containing ink for image formation may be used. The ink cartridge is often discarded after running out of the ink. However, this leads to an increase in running cost and runs counter to the effective utilization of resources. Thus, refillable ink cartridges have been proposed and are widely known, which can be refilled with ink.
In one example of such a refillable ink cartridge, Japanese Patent No. 3799967, a used ink cartridge is refilled with ink and then its ink supply opening portion is affixed with a sealing tape. In another example, Japanese Patent No. 3639836, the ink cartridge has an ink refill opening to which a sealing member is attached in advance so that the refill opening can be sealed with the sealing member. In yet another example, Japanese Patent No. 3667750, an ink inlet is capped and further an adhesive-coated aluminum tape is affixed onto the cap, where the ends of the tape are bent onto each side of the cartridge. Covering an ink supply opening portion of a used ink cartridge with a sealing member for purposes other than refilling is conventional (see Japanese Laid-Open Patent Application No. 10-006523).
In these refillable ink cartridges, the ink supply opening portion is sealed after a refill using the various sealing members mentioned above because the supply opening of the original ink cartridge is left open after use. However, the sealing property of the sealing member may be degraded, or it may be insufficient when the ink is of quick-drying type.
To overcome these problems, an ink cartridge is proposed (Japanese Laid-Open Patent Application No. 2004-284094) in which an ink bag fitted with a retaining member is housed in a casing, wherein the ink bag has an ink supply opening portion (ink discharge opening). The ink supply opening portion is sealed with a resilient sealing member, which is retained by a cap member.
In this ink cartridge, the sealing member at the ink supply opening portion is pierced by a hollow needle-shaped member as part of an image forming apparatus, whereby the inside of the ink bag and the apparatus are communicated to allow the supply of ink. When the ink cartridge is detached from the apparatus main body, the sealing of the ink supply opening portion is maintained by the resilient force of the sealing member.
Such an ink cartridge can be refilled with ink by piercing the sealing member at the ink supply opening portion with a filling device such as a syringe, thus obtaining a refilled ink cartridge.
In this case, although the ink supply opening portion is sealed with the sealing member upon refill, the sealing member may be damaged by the needle-shaped member as it pierces the sealing member during a refill operation. If such a damage is present, the sealing property of the sealing member may decrease and become insufficient, resulting in the leakage of the ink through the pierced opening formed in the sealing member during transport or storage.